| 摘要 |
PURPOSE:To prevent malfunction by effecting reliable earthing of static electricity with which a disc is charged through improvement of conductivity of a magnetic fluid seal. CONSTITUTION:A protrusion 21 is integrally protruded from the inner peripheral surface of a pole piece 10 toward the shaft 2 side. The protrusion 21 is caused to make access to the shaft 2 or brought into contact therewith to improve conductivity. Thus, static electricity with which a hard disc is charged makes contact with a ground through a motor hub, a pole piece 10, and the shaft 2. This constitution reliably removes static electricity with which the disc is charged and reliably prevents malfunction. |
